This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 3 |
| 5 | 15 |
| 6 | 45 |
| 7 | 315 |
| 8 | 315 |
| 9 | 2835 |
| 10 | 14175 |
| 11 | 155925 |
| 12 | 467775 |
| 13 | 6081075 |
| 14 | 3869775 |
| 15 | 638512875 |
| 16 | 638512875 |
| 17 | 10854718875 |
| 18 | 8881133625 |
| 19 | 1856156927625 |
| 20 | 9280784638125 |
| 21 | 194896477400625 |
| 22 | 2143861251406875 |
| 23 | 2595200462229375 |